A very popular type of window covering includes a plurality of separate slats which hang vertically from a headrail in front of the window. The slats can be raised or lowered to any predetermined height to allow a portion or substantially all of the window to be completely visible and permit the passage of light therethrough. In addition, the angular relationship of the slats to one another can be adjusted by a device frequently referred to as a "tilter" which angularly rotates the slats about the their longitudinal axes thereby varying the space between the slats through which light can pass.
A fully satisfactory tilter apparatus should provide means for preventing or reducing the amount of possible tilting force being applied to the slats when they have reached either of their two extremes in adjustment. Otherwise, if excessive force is applied to the slats at one of its extremes of adjustment, this can damage or break adjusting cords typically used to rotate the slats, or damage or substantially impair the functioning of the tilter apparatus itself.
In the past, approaches to solving this problem have included spring-loaded members or spring-loaded clutches which upon experiencing some predetermined amount of maximum force slips or otherwise interrupts the application of additional force to the tilting apparatus, and to the slats and adjustment cords as well. Such mechanisms are relatively expensive to manufacture and are subject to a relatively high-frequency failure rate in operation in that the springs either weaken or break leaving the apparatus nonfunctioning or perhaps leaving the entire tilter mechanism inoperative requiring repair or replacement of the mechanism, or in some case even replacement of the entire blind.
It has also been standard practice in the past to incorporate the tilter mechanism integrally within the headrail from which the blind is supported, by affixing the mechanism to the head rail through the use of rivets, screws or the like. When this is done, if there is any repair or replacement of the tilter mechanism this may result in the replacement of the entire headrail with included mechanism, or, in many cases, it may mean the complete loss of a functioning blind. Also, of course, the use of screws or rivets or other permanent securing means for locating a tilter mechanism within the headrail is a relatively expensive and complex manufacturing process.
However, it is essential that the tilter mechanism be anchored securely within the headrail since it experiences substantial reactive forces during tilting adjustment which, if not counterbalanced by a secure affixing to the headrail, could result in a complete dislodgement of the tilter mechanism and consequent failure of blind operation.